A Brief History of Quarantine and the Little Yellow Flag at CDC

Working at an airport you meet people from most walks of life from almost everywhere.  We catch them coming or going or just grabbing a quick bite on a layover.

Unfortunately sometimes we meet them on their less than best day, not feeling their best and needing some help to get better before they continue on.

Still other times we have to hold them against their will for the health of the greater community.  Well, we as EMS don't do that, the authority to do so lies with the CDC Quarantine Center, who I happen to have on speed dial #2.

At a recent planning meeting I was talking with my friends from CDC and noted the insignia on their uniform.  They have rank insignia on their epaulets and a small golden flag.  As the meeting broke I stood up and asked jokingly, "Is that the flag you wave when someone is sick?"

Her response "Yes, actually, it is."

I sat back down.  "Do tell."

To better understand why she wears a yellow flag on her uniform, we have to go back to 14th century Venice, Italy.

1340 Venice is a major port and trade hub.  People are coming in from all over the globe and bringing with them every type of fever, pox and infection known to humans at the time.  One of these diseases was the black death, which at the time killed 30% of the population.  Of course they didn't know how the diseases were being transmitted, only that sick people on boats became more sick people on land.  Or on canals...it is Venice after all.

This lead to the City leaders enacting a policy where all incoming ships would anchor off Venice and wait for 40 days and 40 nights.  After that time, they believed anyone who was sick would show sickness and either die or be denied entry to Venice.  In Italian 40 days is quaranta giorni. 

Say it fast and you have "Quarantine."

Ships that were sitting for 40 days flew a yellow and black checkered flag later called the Yellow Jack to signify they were still in their 40 day cycle.

Later, ships adopted the practice of flying a yellow flag on the 41st day, signaling they were ready for inspection and asking permission to approach the harbor.

That was 600 years ago.

Today, they yellow flag is still seen as a signal of a ship reporting they are free of disease and ready to enter port.  It is solid yellow and is designated "Q."

This image shows a modern day cruise ship entering port flying three flags:
The flag of their company, an American flag (American port) and Q, stating to local officials that they are disease free and ready for inspection.

The CDC Officers I work with still wear this symbol, an international sign to ship crews and airline companies that they are the health inspection service and hold powers to deny entry.

This symbol really is important when you think about it and I love that it is still worn proudly by the Quarantine Station staff.